EV Automotive System

1. AUTOMOTIVE
SYSTEMS
CAR AS A COMPLETE SYSTEM

2. Automotive Systems:
1.Lubrication System
2.Cooling System
3.Fuel Supply System
4.Transmission System
5.Steering and Suspension System

3. INTRODUCTION
Automobile has become an important influence on the history, economy, and social life of much
of the world.
Structure of the automobile
● Hundreds of individual parts make up the essential components of the modern automobile.
Much like the human body, these parts are arranged into several systems, each with a
different function.
● Each system is necessary for making the automobile run, keeping it safe, and reducing
noise and pollution.
● The major systems of an automobile are the engine, fuel system, exhaust system, cooling
system, lubrication system, electrical system, transmission, and the chassis. The chassis
includes the wheels and tires, the brakes, the suspension system, and the body.
● These systems will be found in every form of motor vehicle and are designed to interact
with and support.

5. LUBRICATION SYSTEM
● Lubrication is required for maintenance of engine. As we know, our body requires fluids like water
and also oil in the form of fats like ghee, butter, cooking oil for maintenance of our system.
● Lubrication system is one of the most important parts of an engine. The engine cannot run
smoothly for more than a few minutes without the lubricating oil.
● Whenever two metallic surfaces move over each other under direct contact, dry or solid friction
is produced. This is due to the irregularities on the two surfaces interlocking each other. The dry
friction thus created produces a lot of heat and results in wear and tear of the metal surface.
Objectives of Lubrication:
The main objectives of lubrication are:
(i) to reduce friction between moving parts to its minimum value so that power loss is minimised, and
(ii) to reduce wear and tear of the moving parts as much as possible.

6. Lubrication also serves other important purposes, which may be called secondary. These are as
follows.
(a) To provide cooling effect: The lubricating oil takes heat from the hot moving parts during
its circulation and delivers it to the surrounding air through the crankcase.
(b) To provide cushioning effect: The lubricating oil also serves as a good cushion against the
shocks experienced by the engine. For example, instant combustion of the fuel in the combustion
chamber produces a sudden rise of pressure in the cylinder and the shock goes to the bearings
through the piston, gudgeon pin and the connecting rod. This shock is then absorbed by the layer of oil
present in the main bearings.
(c) To provide cleaning action: The lubricating oil serves another useful purpose of providing a
cleaning action. During its circulation, it carries away many impurities, such as carbon particles, etc.
(d) To provide a sealing action: The lubricating oil also helps the piston rings in maintaining an
effective seal against the high pressure gases in the cylinder thus preventing leakage towards the
crankcase.

8. COOLING SYSTEM
Like our body requires air and water for cooling our system, similarly the engine of a
vehicle also requires cooling. The cooling system has three primary functions, which
are as follows.
(i) Remove excess heat from the engine
(ii) Maintain a constant engine operating temperature
(iii) Increase the temperature of a cold engine as quickly as possible by maintaining
the thermostat valve in a closed position which is fitted in the path of coolant
circulation

9. Necessity of Cooling
● The cylinders of internal combustion engines require cooling because the
engine cannot convert all the heat energy released by combustion into
useful work.
● Liquid cooling is employed in most of the IC engines, whether they are used
in automobiles or elsewhere.
● The water (coolant) is circulated around the cylinders to pick up heat and
then dissipate it through a radiator.
● As the temperature increases from 71 to 82 degrees centigrade, the
thermostat valve opens and sends water to the radiator to radiate the
heat.
● When the temperature rises above 82 degrees, the thermostat switch
operates the cooling fan to support the cooling process in radiator.

11. FUEL SUPPLY SYSTEM
● In petrol engines, the fuel and air mixture is supplied to the combustion chamber of an
engine. This mixture is atomised and then vapourised by the carburettor. Then the
mixture is ignited by the spark plug.
● The fuels, such as petrol, benzoyl and alcohol are used in an SI engine. Nowadays, fuel is
injected in the flow of air at a certain temperature and pressure and the fuel evaporates
faster and the combustion process is better, with low emission. It also shows better fuel
efficiency.
● In case of compression ignition engine (diesel) the fuel is sent through the fuel pump to
the injector and the injector sprays the fuel at end of compression stroke.
● The oil fuels which are used in CI engines do not evaporate easily. Therefore, a separate
injection system is used consisting of fuel injection pump (FIP) and injectors. These
injectors atomise the fuel and it is then sent for combustion.
● Nowadays, in case of compression ignition engine the common rail direct injection system
(CRDI) is used for better engine performance.

12. Fuel Supply Components
The fuel supply components include the following:
1. Fuel Tank: In most of the vehicles the fuel tank is located at the rear end of the vehicle. The
fuel tank is made of a metal sheet or plastic. It is attached to the chassis. The filler opening is closed
with a cap. The fuel line is attached to the fuel pump and also to the fuel gauge.
2. Fuel Line: The fuel line carries the fuel from the fuel tank to the carburettor or to the common
rail system used in MPFI engines. The line has to withstand the pressure and provide resistance for
the corrosion. The rigid line is placed safely in the chassis. It is connected to the units like
carburettor, through a flexible pipe.
3. Fuel Filter: The major role of the fuel filter is to send clean fuel to the engine. This prevents
blockages in the fuel system. The filter contains a cartridge of filtering the element through which
the fuel passes the filter traps any particles and prevents them from entering the fuel system. The
fuel filter is required to be replaced at regular intervals.

13. 4. Air Cleaner: It is the main unit of the fuel system. It supplies clean air to the engine. The element of
the air cleaner must be cleaned and replaced at regular intervals for maintaining a healthy life of the engine.
5. Fuel Injection Pump: In case of a diesel engine, the diesel oil from the fuel tank is sucked by the
fuel feed pump. The pump first sends the diesel oil to the fuel filter. From there it is sent to the transfer
pump. The transfer pump increases the pressure of the fuel. This high pressure of the fuel is then
transferred to the distributor rotor through the metering valve. From the rotor the fuel is sent to the
injector. In case of multi-point fuel injection system the electric fuel pump is used. The pump generates the
injection pressure and sends it to the fuel filter and then to the common rail at a pressure of 3 to 4 bar. The
common rail or fuel rail is connected to the fuel injector.
6. Fuel Injector: The solonide injector used in the M.P.F.I fuel system is operated electrically as per the
variation in the supply of current with resistance. The solonide winding induces current within it and controls
the movements of the needle valve to inject fuel as per the variations in speed and the load. The fuel system
is controlled by the ECM.
7. Pressure Regulator: It controls the amount of pressure that enters the injector. The extra fuel is
sent back to the fuel tank.

15. TRANSMISSION SYSTEM
Transmission system is used in motor vehicles to supply the output of the internal
combustion engine to the drive wheels. The transmission reduces the higher engine speed
to the slower wheel speed, increasing torque in the process.
The transmission system consists of the following components.
(i) Clutch assembly
(ii) Gear box assembly (Transmission case assembly)
(iii) Propeller shaft
Clutch assembly
Clutch is a mechanism which enables the rotary motion of one shaft to be transmitted,
when desired. The axes of driving shaft and driven shaft are coincident.

16. Functions of clutch
(a) To disconnect the engine power from the gearbox as required, under the following
circumstances:
(i) to start the engine and warm it up;
(ii) to engage first and second gear to start the vehicle from rest;
(iii) to facilitate changing the gear as required; and
(iv) disconnect from the engine to stop the vehicle after application of brakes.
(b) To allow the engine to take up load gradually without shock or jerk.
Requirements of a Clutch
(a) Torque transmission or the ability to transmit maximum torque of the engine.
(b) Gradual engagement, i.e., to engage gradually and avoid sudden jerks.
(c) Heat dissipation, i.e., ability to dissipate large amount of heat generated during the clutch
operation due to friction.
(d) Dynamic balancing, which means that the clutch should be dynamically balanced. This is
particularly required in the case of high-speed engine clutches.
(e) Vibration damping, i.e., having a suitable mechanism to damp vibrations to eliminate noise
produced during the power transmission.

17. Main Parts of a Clutch
The main parts of a clutch are divided into three groups.
(a) Driving members: The driving members consist of a flywheel mounted on the engine
crankshaft. The flywheel is bolted to a cover which carries a pressure plate or driving disc,
pressure springs and releasing levers. Thus, the entire assembly of the flywheel and the cover
rotate all the time. The clutch housing and the cover provided with openings, dissipate the heat
generated by friction during the clutch operation.
(b) Driven members: The driven members consist of a disc or plate, called the clutch plate.
It is free to slide lengthwise on the splines of the clutch shaft (primary shaft). It carries
friction material on both of its surfaces. When it is gripped between the flywheel and the
pressure plate, it rotates the clutch shaft through the splines.
(c) Operating members: The operating members consist of a foot pedal, linkage, release
bearing, release levers and the springs.

18. Gear Box (Transmission Case) Assembly
We need different gear ratios in the gearbox or transmission system to enable the
vehicle to move at different speeds. At the time of starting the vehicle, the
maximum amount of torque is available on the flywheel, for which low gear ratio is
selected for the movement of the vehicle. As the engine speed increases, the
amount of torque is reduced on the flywheel and it is required to select higher gear
ratio.
Functions of a gear box
(i) To provide a means to vary the leverage or torque ratio between the engine and
the road wheels as required.
(ii) The transmission also provides a neutral position so that the engine and the road
wheels are disconnected even with the clutch in the engaged position.
(iii) It provides a means to reverse the car by selecting the reverse gear.

20. STEERING AND SUSPENSION SYSTEM
Steering System
● The steering mechanism permits the driver to control the car on a straight road and turn right or
left as desired.
● The steering mechanism includes a steering wheel, which the driver controls, a steering gear,
which converts rotary motion of steering wheel in to straight line motion and steering linkages.
● In modern cars, the manually operated steering system is assisted by power and is called power
steering. The electric power drawn from the battery or hydraulic power is used.
Functions of a Steering System
1. It provides directional stability to the vehicle when moving in a straight (ahead) direction.
2. It provides perfect steering condition, i.e., perfect rolling motion of the wheels at all times.
3. It facilitates straight ahead recovery after completion of turn.
4. It controls the wear and tear of the tyre.

21. 5. It is used to turn the vehicle as per the will of the driver.
6. It converts the rotary motion of the steering wheel into angular displacement of the front wheel.
8. It absorbs road shocks and prevents them from reaching the driver.
Requirements of a Good Steering System
1. It should be very accurate.
2. It should be easy to handle.
3. The effort required should be minimal.
4. It should provide directional stability.
5. The front wheels should roll without lateral skid while negotiating curves.
6. There should be proper proportion between the angles turned by the front wheels.
7. The tyre must have good elasticity.
8. The wheels should automatically come to the straight ahead position after negotiating the bend.
When going straight, the wheels must maintain the neutral position.
9. The angular oscillations of the wheels must be minimum.
10. The system must be irreversible to a certain degree so that minimum front wheel shocks are
transmitted to the driver’s hands.

22. Steering Mechanism
For perfect steering, it must always have an instantaneous centre about which all the wheels must
rotate. To achieve this the inner wheel has to turn more than the outer wheel.
Two types of mechanism are available, the Davis and the Ackermann steering mechanism. Out of these
Ackermann type is more popularly used because of its simplicity.
Steering Linkages
A steering linkage is the part of an automotive steering system that connects to the front wheels. In a
commercial vehicle a rigid axle type front suspension system is used.
Steering Wheel
It is made of polyurethane or hard plastic. It consists of a circular rim with a hub at the centre. The
rim is slightly elliptical in cross section to maintain strength and provide hand grip.
Steering Shaft
It is made from drop forged alloy steel. It connects the steering wheel to the steering gear box and
transfers movements of the steering wheel to the steering gear, or to the pinion.

23. Steering Column
It is tubular in nature. It provides switches for horn, light and wiper for easy and quick operation. The
collapsible columns are used for safety, which collapse upon impact and reduce the chances of injury to
the driver.
Drop Arm
It is also called as pitman arm. It is made up of drop forged steel. It connects the cross shaft with
the drag link.
Drag Link
It connects the drop arm to the steering knuckle. It is also made up of drop forged steel.
The tie rod ends are different parts of the steering linkage will be connected to the ball joints which
provide angular motion to the steering system.
Steering Gears
The steering gear converts the turning motion of the steering wheel into the to-and-fro motion of the
link rod of the steering linkage.
It also provides the necessary leverage so that the driver is able to steer the vehicle without fatigue.

25. Suspension System
● Suspension is the term given to the system of springs, shock absorbers and linkages that
connects a vehicle to its wheels.
● The suspension system serves a dual purpose, contributing to the vehicle’s road holding or
handling and braking for safety and driving comfort, and keeping the vehicle occupants
comfortable and reasonably well isolated from road noise, bumps and vibrations, etc.
Functions of suspension system
The main functions of a suspension system are as follows:
(i) To safeguard the occupants against road shocks and provide riding comfort.
(ii) To minimise the effects of stresses due to road shocks on the mechanism of the motor vehicle and
provide a cushioning effect.
(iii) To keep the body perfectly in level while travelling over rough uneven ground, i.e., the up and down
movement of the wheels should be relative to the body.
(iv) To isolate the structure of the vehicle from shock loading and vibration due to irregularities of the
road surface without impairing its stability.
(v) To provide the requisite height to the body structure as well as to bear the torque and braking
reactions.

26. Various Components of Suspension System
The components of a suspension system can be categorised as follows.
1.Mechanical Suspension
(i) Leaf springs
(ii) Coil springs
(iii) Rubber springs
(iv) Torsion bars
2.Hydraulic Suspension
(i) Hydraulic shock absorber
(ii) Telescopic fork absorber
3.Air Suspension
In this suspension, compressed air is used as a spring. This suspension system is operated with air and
controlled by a microprocessor. It helps in maintaining self-driving conditions and supports the weight
of the vehicle.

27. Mechanical Suspension
1. Leaf Spring: A leaf spring is a component of a vehicle's’ suspension system. Leaf springs are
curved and the curvature helps the spring absorb impact.
2. Coil Spring: Coil springs are commonly called compression springs, torsion springs or helical
springs. They store energy and release it to absorb shock or maintain a force between two contacting
surfaces. Mostly coil springs or helical springs are used in engine starter and hinges.
3. Rubber Spring: A rubber string stores more energy per unit mass than any other type of spring
material.
The rubber spring is installed between the frame and the top link of the suspension system. When the
spring is connected to a point near the link pivot, deflection of the spring reduces to a minimum,
without affecting the total wheel movement.
The energy released from the rubber spring after deflection is considerably less than that imparted
to it.
4. Torsion Bars: Torsion bars are of two types — helical or spiral. These bars are used in
automobile vehicles for transmitting torque.

28. Hydraulic Suspension
● Hydraulic suspension combines rubber springs with a damper system, linking the front and
rear wheel on the same side of the car.
● As the front wheel rises over a bump, some of the fluid from its suspension unit (known as
a displacer unit) flows to the rear-wheel unit and raises it, so tending to keep the car
level.
● In each of the displacer units, the fluid passes through a two-way valve, which provides
the damping effect.
● Once the rear wheel has passed over the bump, the fluid returns to the front displacer
unit and the original level is restored.
1. Hydraulic Shock Absorber: It is a mechanical device designed to absorb shock
impulses. This device is also used for checking or damping out the suspension spring to a
comfort level.
2. Telescopic Fork Absorber: A telescopic fork is a form of motorcycle front
suspension whose use is so common that it is virtually universal. The telescopic fork uses fork
tubes and sliders which contain springs and dampers.

29. “If I had asked people what they wanted,
they would have said faster horses.”
- Henry Ford

30. Thanks!
Keerti Krishnan
Dayalbagh Educational
Institute Agra
keertik039@gmail.com